IBM's SVC gets thin provisioning

One of the top block storage virtualization products, IBM's SVC, just got better. It is getting thin provisioning, confirming a virtual pre-announcement in April.

SVC - SAN Volume Controller - virtualizes multiple IBM and non-IBM drive arrays in a storage area network (SAN) into a single logical pool of storage for use by applications in connected servers. It functions as a product linked to the main director unit in a SAN and its internal SAN fabric placement contrasts with that of its main competitor, Hitachi Data Systems' USP, which is placed as a special head controller between the SAN drive arrays and the fabric edge.

Such virtualization improves storage utilization and eases storage migration from array to array.

IBM claims it is both the performance and unit ship leader in block storage virtualization with the fastest system tested in the industry and the shipping of over 12,000 SVC engines running in more than 4,000 SVC systems. The company is presenting its SVC improvements in terms of increased power efficiency and 'greeness' through reduced disk drive capacity wastage.

The company includes storage virtualization as one of the five pillars of its Big Green initiative.

Barry Rudolph, Storage Stack Solutions VP for IBM, said: "We have been the leader in storage virtualization since SVC was introduced five years ago, and this latest version from IBM further showcases our innovation and represents our commitment to clients to incorporate green, efficient technologies into our storage portfolio to help clients manage the data center crisis of today."

IBM's SVC 4.3 software includes the following enhancements:

Thin provisioning with Space-Efficient Virtual Disks (SEV) which use disk space only when data is written instead of reserving disk space for the entire capacity of a virtual disk. This reduces the neeed to pre-buy disk capacity.

Space-Efficient FlashCopy (SEFC) which uses disk space only for changes between source and target data and not for the entire capacity of a virtual disk copy. This could help reduce space required for copies by as much as 75 percent or more.

Virtual Disk Mirroring (VDM) helps improve availability for critical applications by storing two copies of a virtual disk on different disk systems,

Thin provisioning has been offered by vendors such as 3PAR for some years already. IBM's implementation means that any storage array virtualized bt the SVC can now be thinly-provisioned, whether the original supplier supports it or not.

SEFC can benefit prolific virtual machine users with multiple copies of boot files. Cloning them now takes up much less room.

IBM reckons that VDM means you can upgrade cheap low-rate RAID controller arrays up to enterprise reliability levels by mirroring between them using VDM.

IBM reckons it has a better thin provisioning implermentation than HDS; meaning it can be thinner, and also that the thinness can be varied. Blogger Barry Whyte writes: "We've gone for fine-grained Space Efficiency, and allow you to modify the chunk, or grain size from 32K up to 256K in powers of 2. I personally believe we also have the fastest performing fine-grained SEV implementation on the market."

Other SVC additions include:

Support for 8,192 Virtual Disks - twice as many as before,

256 FlashCopy Targets,

IPv6 support - Both SVC and its master console or SPCC,

Brocade 8Gbit SANs fabric connectivity.

IBM also announced a new release of the IBM System Storage Productivity Center (SSPC), which now includes TotalStorage Productivity Center for Replication 3.4 pre-installed, providing simplified management of the copy services offered by SVC FlashCopy, and Metro and Global Mirror.

The new IBM SAN Volume Controller 4.3 functions are available at no additional charge and existing SVC customers will be able to take advantage of these improvements when they upgrade to SVC 4.3. Space-Efficient FlashCopy requires a license for the FlashCopy function. The new SVC 4.3 software will be available for download on June 27, 2008.